Marine Mammal Ecology

1. Marine Mammal Ecology Ecology : An attempt to describe and explain the patterns of distribution and abundance of organisms. These patterns reflect the history of complex interactions with other organisms as well as the environment. Marine mammal ecology is had to get data on. Marine mammals live in the ocean, which makes everything harder Marine Mammal Protection Act prohibits many techniques typically used to study animals

2. Marine Mammal Physiology Constraints of a Marine Existence Breath-Holding (Apnea) for Diving Marine Mammals are good divers Sperm whale can stay under for >2hrs diving 1000-2000m Hooded seals exceed 1000m, staying under for >50min

3. Asphyxia • Asphyxia: The combined effects of lack of oxygen (hypoxia), increased carbon dioxide, and the accumulation of the products of anaerobic metabolism, such as lactic acid and hydrogen ions • Aerobic metabolism sustains the brief dives as well as the first parts of the deeper dives, but in longer dives it switches to anaerobic metabolism.

4. Diving Adaptations • Oxygen storage • Relative to body size, marine mammal lung capacities are not much greater than terrestrial mammals. • Oxygen storage is increased in the blood and muscles and they have more blood than terrestrial mammals. • The oxygen storage potential in blood and tissue is correlated with the diving abilities of the animal.

5. Diving Adaptations • Diving Bradycardia (Decreased Heart Rate) • Low heart rates (5% of predive rate) have been recorded in phocids • Dolphins can reduce their heart rates from 100 to 12 beats/min.

6. Diving Adaptations • Preferential distribution of oxygen to various body tissues during apnea. • Mammalian Diving Response: Regional vasoconstrictuion within those organs that tolerate a prolonged lack of oxygen. This selective ischemia (when tissues are deprived of circulating blood) lowers the metabolism of those tissues are reduces asphyxia. • Blood is drawn from areas of less importance to areas of greater importance. • Sufficient blood pressure is maintained for perfusion of the vital organs, brain and heart.

7. UnderPressure • Pressure increases by 1 atmosphere for every 10m of depth • Therefore, the weddell and elephant seals regularly experience 50 to 100 atmospheres of pressure.

8. Adaptations to Pressure • Barotrauma-damage caused by rapid expansion or squeezing of gas spaces that exceeds the structural integrity of tissues. • Lung Squeeze- when the tissues deform to the point of stress. Limits human breathing dives to about 30m. • Deep diving marine mammals have flexible chest walls and other structures capable of sufficient collapse to render the lungs airless. • This keeps air from coming in contact with tissues at high pressures and thus removes the possibility of the “Bends”, Nitrogen Narcosis, Oxygen Toxicity and Hypoxia.

9. Water and Salt Balance • Osmosis: The movement of water and salt across a permeable membrane due to a differential in concentration across that membrane. • If you have a body of high salt concentration (and therefore low water concentration) sitting in an environment of lower salt concentrations (and therefore high water concentration), water will flow into the body and salt will flow into the environment. • The reverse also occurs. • Can result in dessication (losing too much water), or plasmolysis (the rupturing of cells that get filled with water).

10. water molecules protein molecules semipermeable membrane between two compartments Fig. 5-12, p.84

11. 2% sucrose solution 1 liter of 10% sucrose solution 1 liter of 2% sucrose solution 1 liter of distilled water Hypotonic Conditions Hypertonic Conditions Isotonic Conditions Fig. 5-13, p.85

12. first compartment second compartment hypotonic solution hypertonic solution membrane permeable to water but not to solutions fluid volume rises in second compartment Fig. 5-14, p.85

13. water gain by osmosis does not drink water solutes pumped in by cells in gills water loss in large volume of dilute urine Freshwater bony fish (body fluids far saltier than surroundings) Fig. 42-3a, p.740

14. water loss by osmosis drinks seawater water loss in very small volume of urine solutes pumped out by cells in gills Marine bony fish (body fluids less salty than surroundings) Fig. 42-3b, p.740

15. Osmolality • Osmolality (osmotic potential) of sea water is about 1000 mOsm/kg. For humans, it’s about 290 to 300 mOsm/kg and for seals it is about 330mOsm/kg • In order make up the difference marine mammals remove excess salts in very salty uring (2000 to 4000 mOsm/kg) • Kidneys • Primary site of water conservation as well as electrolytes and other substances necessary for life • Marine mammals have very large kidneys, that receives a lot of metabolic energy.

16. kidney cortex kidney medulla renal artery renal vein renal pelvis renal capsule ureter Fig. 42-5c, p.742

17. Bowman’s capsule (red) proximal tubule (orange) distal tubule (brown) KIDNEY CORTEX KIDNEY MEDULLA loop of Henle (yellow) collecting duct (tan) Fig. 42-6a, p.743

18. efferent arteriole afferent arteriole glomerular capillaries inside Bowman’s capsule peritubular capillaries threading around tubular nephron regions Fig. 42-6b, p.743

19. a) Filtration b) Tubular Reabsorption proximal tubule distal tubule glomerular capillaries c) Tubular Secretion CORTEX MEDULLA peritubular capillaries loop of Henle increasing solute concentration d) Urine urine outflow from collecting duct into renal pelvis Fig. 42-7, p.744